1. Field of the Invention
The invention relates generally to receivers and in particular, a remote monitoring system receiver used with a power distribution network for providing information over the power lines of a network, said receiver having a dual baud rate selector.
2. Description of the Prior Art
Remote monitoring systems which are used in conJunction with power distribution networks are well known in the prior art. For example, U.S. Pat. Nos. 4,535,447, 4,550,416 and 4,583,073 describe the various features of remote monitoring system transmitters. These patents are assigned to the same assignee as this patent and are incorporated herein by reference. Remote monitoring system transmitters are associated with transformers to monitor transformer operation. Each transmitter is connected to the secondary power distribution network. At some remote point from the various transmitters, a remote monitoring system receiver is also connected to the secondary power distribution network. The transmitters and receivers communicate so that the receiver is provided with a summary of the information reflecting the status of each transformer having a transmitter.
The original system design of a remote monitoring system provided for access by remote equipment originating data links by means of a standard 300 baud telephone channel using off-the-shelf modem interfaces. This is compatible with most equipment that is available in the utility industry and, in particular, is compatible with portable terminals which are part of the utility operational plan for remote monitoring systems.
The proliferation of computing equipment, particularly, the availability of personal computers with auto dialers, has created a need for more flexible interfaces with the RMS systems. One feature that is in demand is the ability to run at a higher baud rate without sacrificing the capability of the 300 baud rate operation. Operation at a higher baud rate is an attractive feature but the 300 baud rate interface must be maintained. The functional requirement, therefore, is to have one or more ports of the RMS receiver operating automatically at either a 300 baud rate or a 1200 baud rate with the rate determined by the remote equipment originating the data link.
There are equipments available today that have the capability of responding to multiple baud rates automatically. However, these equipments generally use a software subroutine to identify the baud rate of the incoming data and iteratively adjust the responding baud rate to match. In contrast, the invention meets the requirement of providing both a B fixed low rate (300 baud) and a fixed high rate (such as 1200 baud) operation automatically at each data access point.